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Contamination, can be defined as the contamination or contamination of an environment by any means by unwanted substances such as pollutants, waste, microorganisms.
In order to control the contamination of airborne particles to remain within the contamination limits accepted in sensitive activities, a standard for clean rooms and controlled environments with these rooms has been prepared.
Products and processes that benefit from the control of airborne contamination include products and processes in industry branches such as space, microelectronics, pharmaceuticals, medical devices, food and medical care.
The ISO classification used in defining the cleanliness of the air in clean rooms and controlled environments is divided into limits. The criteria of the TS EN ISO 14644-1 standard, which entered into force on 18.02.2016 and describes the standard test method as well as the determination of the concentration of airborne particles, can be summarized as follows.
For classification purposes, a designed size range is given for the particles in question to determine the particle concentration limits.
Standard protocols are given for determining and designing cleanliness levels based on airborne concentration of particles larger or smaller than the designed particle size range in the classification.
It is one of the series of standards related to clean rooms and contamination control. In addition to the factor of being free from airborne particles, many other factors should be taken into account in the design, definition, use and control of clean rooms and other controlled environments. These are detailed in other parts of the international standards prepared by ISO/TC 209. In some cases, additional methods and limitations may be given by the competent regulators on the subject. In such cases, appropriate adaptations of the standard test procedures may be necessary.
d. It covers the classification of air cleanliness of clean rooms and environments controlled together in clean rooms, especially according to the airborne particle concentration. In the classification, only the cumulative distribution of particle populations based on the spread in the threshold range of 0.1 μm to 5 μm, which is the lowest limit, has been taken into account.
The standard does not cover the classification of particle populations outside the specified sizes within the range of 0.1 μm to 5 μm. The concentrations of particles smaller than 0.1 μm and macro particles larger than 5 μm can be used to quantify these populations with the U and M descriptors, respectively.
The standard cannot be used to specify the physical, chemical, radiological or permeable structures of airborne particles. Due to the increase in size distribution, the final distribution in particle concentrations is naturally unpredictable and typically variable over time.
Classes according to ISO 14644-1 standard:
Particle testing procedures in sterile areas such as clean rooms, operating rooms and intensive care units should be performed once a year as part of general HVAC performance testing procedures. In sensitive areas where injectable filling is performed, such as TPN units, it is recommended that the test period be determined as 6 (six) months.
We cannot evaluate hygienic ventilation systems that do not have an automation system that will ensure the continuity of clean room conditions as compliant with the standard. In principle, the ventilation system must have undergone installation testing and inspection prior to performance tests. HVAC performance tests and installation inspection and tests are separate tests and should not be confused.
The main headings to be considered in the installation of a hygienic ventilation system can be listed as follows;
In the first stage, a project and specifications should be prepared in accordance with current standards by an engineering company with experience and expertise in the field.
It should be ensured that the products such as hygienic air conditioning unit, laminar flow unit, hepa filter, hepa filter box to be used in the application meet all international standards, especially sealing.
The most important factor to be considered at the beginning of the application is that the duct leakage tests must be performed in accordance with the standards. Concluding that the tests have been successfully completed as a result of some smoke tests may create unexpected high costs for the investor in the future. In the tests, the leakage class of the channels must be determined by using a channel leakage test device.
Channel leakage tests must be started in the first days of channel production and must continue until the manufacturing is completed. When we consider the possibility of improper manufacturing, it is necessary not to forget the risk of dismantling the entire channel after the manufacturing is completed.
If channel leakage tests are not performed, the operator will suffer from high-cost leakage air for years It should not be forgotten that the necessary amount of air in the hygienic area will be lost due to this, and that negative results will be obtained from the validation tests.
It is not possible to perform duct leakage tests after the connection of the power plant and the establishment of the HEPA filter output terminals. For this reason, the process should be followed very well and the tests should definitely be done on time.
Unless duct leakage tests are performed, air leaks negatively affect the business and the country’s economy, causing energy resources to be wasted.
The automation system that ensures that hygiene conditions are maintained in ventilation throughout the year should be established with an appropriate scenario and all scenarios should be carefully simulated and tested one by one.
Before receiving the ventilation system from the contractor, the investor should definitely have the validation tests done by an impartial and expert organization.
It is not ethically appropriate for the contractor to validate the system they have made themselves. The company you will have these tests done should be accredited by TÜRKAK. It should be noted that the testing company is authorized in the relevant clean room names and within the scope of the relevant international standard within the scope of accreditation.
İlker KURAN
Alperen Ltd. Şti.